|Elucidation of binuclear non-heme iron enzyme intermediates|
: 291 : 2015.04.27 09:51
|일시 : 2015.04.29 17:00|
|소속 : KAIST, Department of Chemistry|
|발표자 : 박기영|
|장소 : R404|
Binuclear non-heme iron enzymes perform a wide range of chemistries that are essential for aerobic metabolism. This class of enzymes utilizes a coupled diiron cofactor and activates O2 to perform H-atom abstraction, desaturation, hydroxylation, electrophilic aromatic substitution, and so on. During the activation of O2, the diiron cofactor undergoes several intermediate states, which include peroxy-level and high-valent Fe-level intermediates. To understand the diverse chemistry of the diiron cofactor, these oxygen intermediates have been characterized by employing various spectroscopic techniques, such as nuclear resonance vibrational spectroscopy, circular dichroism (CD), magnetic CD (MCD), variable-temperature, variable-field MCD, and resonance Raman spectroscopies, and density functional theory computations. Two peroxy intermediates are known to exist, while only one of them is poised for O-O bond cleavage. Structural differences between these two have been defined, and their differences in electrophilic reactivity have been clarified. This understanding of the peroxy-level intermediates is key to elucidating the mechanisms of class Ia ribonucleotide reductase (RR) and soluble methane monooxygenase (MMO), where the peroxy intermediates further convert to reactive high-valent intermediates that abstract an H atom from Tyr in RR and from CH4 in MMO.